ci(wsl): run the WSL2 nightly from a nextest archive

The nightly has failed since 10-05 with LNK1327: the contract step
re-invoked cargo with TEMP on \\wsl.localhost, cargo re-linked the lib
tests, and mt.exe cannot create its manifest temp file on a UNC path.

Build the lib tests once into a nextest archive with the native TEMP,
and run both the contract test and the lib suite from that archive, so
nothing is built while TEMP points at the WSL share. The archive is
extracted to the runner temp, and --no-tests fail replaces the manual
check that the contract test was discovered.

Supersedes #6856.

.github/workflows/wsl2-nightly.yml

@@ -12,6 +12,11 @@ name: WSL2 Nightly
 # which all create the app database, are not run. Tests run under cargo-nextest
 # one at a time, so a hung test is killed by the per-test timeout in
 # src-tauri/.config/nextest.toml instead of eating the whole job.
+#
+# The tests are built once into a nextest archive with the native TEMP, and the
+# run steps execute that archive. Invoking cargo with TEMP on \\wsl.localhost
+# can re-link the crate, and link.exe/mt.exe cannot create manifest temp files
+# there (LNK1327).
 on:
   schedule:
     - cron: "23 18 * * *" # 02:23 Beijing time
@@ -82,32 +87,35 @@ jobs:
           "CC_SWITCH_WSL_TEST_DIR=$testRoot" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
           "CC_SWITCH_WSL_TEST_TEMP=$testTemp" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
 
-      - name: Compile backend tests with native temp
-        # link.exe/mt.exe cannot create manifests when TEMP points at a WSL UNC path.
-        run: cargo test --lib --manifest-path src-tauri/Cargo.toml --no-run
+      # link.exe/mt.exe cannot create manifests when TEMP points at a WSL UNC path,
+      # so build here with the native TEMP and only run the archive below.
+      - name: Archive backend lib tests with native temp
+        shell: pwsh
+        run: |
+          $archive = Join-Path $env:RUNNER_TEMP "cc-switch-lib-tests.tar.zst"
+          $extractDir = Join-Path $env:RUNNER_TEMP "cc-switch-lib-tests"
+          # --extract-to requires an existing directory
+          New-Item -ItemType Directory -Force -Path $extractDir | Out-Null
+          cargo nextest archive --lib --manifest-path src-tauri/Cargo.toml --archive-file $archive
+          if ($LASTEXITCODE -ne 0) {
+            exit $LASTEXITCODE
+          }
+          "NEXTEST_ARCHIVE=$archive" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+          "NEXTEST_EXTRACT_DIR=$extractDir" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
 
+      # Running from the archive never invokes the build. The binaries are
+      # extracted to the native runner temp, not to TEMP on \\wsl.localhost.
+      # --no-tests fail turns a renamed or cfg'd-out contract test into a failure.
       - name: Run Windows-to-WSL2 filesystem contract
         shell: pwsh
         run: |
           $env:TEMP = $env:CC_SWITCH_WSL_TEST_TEMP
           $env:TMP = $env:CC_SWITCH_WSL_TEST_TEMP
-          $testName = "config::tests::atomic_write_replaces_existing_wsl_unc_file"
-          $testList = cargo test --lib --manifest-path src-tauri/Cargo.toml -- --ignored --list
-          if ($LASTEXITCODE -ne 0) {
-            exit $LASTEXITCODE
-          }
-          $expected = "${testName}: test"
-          if ($testList -notcontains $expected) {
-            throw "Expected ignored test was not discovered: $testName"
-          }
-          cargo test --lib --manifest-path src-tauri/Cargo.toml $testName -- --ignored --exact --nocapture
-          if ($LASTEXITCODE -ne 0) {
-            exit $LASTEXITCODE
-          }
+          cargo nextest run --archive-file $env:NEXTEST_ARCHIVE --extract-to $env:NEXTEST_EXTRACT_DIR --extract-overwrite --profile ci --no-tests fail --no-capture --run-ignored only -E 'test(=config::tests::atomic_write_replaces_existing_wsl_unc_file)'
 
       - name: Run lib tests against WSL2-backed home
         shell: pwsh
         run: |
           $env:TEMP = $env:CC_SWITCH_WSL_TEST_TEMP
           $env:TMP = $env:CC_SWITCH_WSL_TEST_TEMP
-          cargo nextest run --lib --manifest-path src-tauri/Cargo.toml --profile ci --test-threads 1 -E 'not test(/database::/)'
+          cargo nextest run --archive-file $env:NEXTEST_ARCHIVE --extract-to $env:NEXTEST_EXTRACT_DIR --extract-overwrite --profile ci --test-threads 1 -E 'not test(/database::/)'